What are the two types of bone architecture?

• A. Compact (Cortical) and Spongy (Cancellous)
• B. Dense and Porous
• C. Cortical and Trabecular
• D. Spongy and Dense

Answer: (A)

Bone architecture comes in two main forms: compact (dense) bone and trabecular (spongy) bone. Compact bone forms the hard outer shell of most bones, tightly packed and organized into structural units called osteons, which gives it great stiffness and strength with relatively low porosity. Inside the bone, trabecular bone has a porous, lattice-like network, providing a lighter, more flexible framework with a large surface area for metabolic activity, remodeling, and housing bone marrow. This inner architecture is especially prominent at the ends of long bones and in vertebrae, while the dense outer layer dominates the shafts. So the two types—compact (cortical) and trabecular (spongy/cancellous)—together make up the common architectural organization of bone.